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Mopho: analog/digital? Keyboard Synthesizers
Old 26th December 2010
  #1
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Mopho: analog/digital?

So, following a heated discussion on a Danish forum I'm fearing I may have to eat some of my words, you be the judge:

Old Nabble - Analogue Heaven - What's analog inside a DSI Mopho?

"The Mopho is a synth on a chip based around a variant on the CEM3396,
the PA397, plus a few important additions: two external FFs used for
sub-oscillators
, a digital noise source, and an external audio input... "

Further down:

"All the waveforms on the Mopho, excluding the suboscillators which are pure digital being nothing more than a couple of flip flops, are generated using a waveshaper on the integrator's ramp wave."

What does that mean, 'flip flops'?

Anyways: All analog audio path? Hmm?

Noise generator aside, the sub-oscillators are digital? Or how should I interpret this info?

PS: I've always thought the overdrive circuit on the Mopho had an odd character, comments ..?
PPS: No 'DCO = digital'-comments please, this is not about DCOs/VCOs.
PPPS: I'm happy with my Mopho, I'm simply curious and am afraid I've been incorrect claiming the oscillator audio path is all analog - not counting noise source which is digital.
Old 26th December 2010
  #2
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The Mopho does have an all analogue audio path. It does run DCOs and the subs are probably digital. The Mopho is one of the best modern synths around and well worth the money!
Old 26th December 2010
  #3
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You could say flip flops are digital but you could just as well call them analog,it isn't important. If you say they're digital then all square waves are digital.
Digital is just a subset of analog. There's really no right or wrong here and is in itself utterly unimportant.

EDIT: Florian Anwander seems to have the right idea. Listen to him,he's a wise man.
EDIT2: Wait,it was Dave Manley who had the right idea. Missed a quote.

In summary, this is one of those stupid recurrent arguments on AH.

Q. Is the Mopho oscillator analog?
A. Wrong question!

Q. Is the Mopho oscillator digital?
A. Wrong question!

Q. What type of oscillator does the Mopho use?
A. Hybrid, it's both analog and digital.
Old 26th December 2010
  #4
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What are 'flip/flops'? What is meant by a 'subset'? How can the audio path be all analog if the sub-oscillators are digital?

Quote:
Originally Posted by jupiter8 View Post
..If you say they're digital then all square waves are digital...
Ok, my technical understanding is limited, but that makes no sense, at all. If something is on/off (1/0) that has nothing to do with digital/analog as in DSP/DCO.

Quote:
Originally Posted by Acid Hazard View Post
The Mopho does have an all analogue audio path. It does run DCOs and the subs are probably digital. ..
That is an oxymoron.

Oh, and did you read my post?
Quote:
Originally Posted by GeorgeHayduke View Post
PPS: No 'DCO = digital'-comments please, this is not about DCOs/VCOs.
PPPS: I'm happy with my Mopho, I'm simply curious and am afraid I've been incorrect claiming the oscillator audio path is all analog - not counting noise source which is digital.
Old 26th December 2010
  #5
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Quote:
Originally Posted by GeorgeHayduke View Post
What are 'flip/flops'?
A flip/flop is a circuit that changes state on a trigger signal. It is 1 (or 5 volts or whatever) trig it and it changes state to 0 (or 0 volt or whatever).
http://en.wikipedia.org/wiki/Flip-flop_(electronics)

You simply cannot say it is either digital or analog,it is both. A square wave can be defined as digital since it shifts between two states. You can also say it is analog since it is that too.
Quote:
How can the audio path be all analog if the sub-oscillators are digital?
That's only a definition, it has no meaning in this case.
Quote:
Did you actually read my post? Reminder:
Yes and it is the wrong question and is utterly unimportant.
Old 26th December 2010
  #6
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Yoozer's Avatar
Quote:
Originally Posted by GeorgeHayduke View Post
What does that mean, 'flip flops'?
It's an interesting logical circuit that can do several things. Sub-oscillators derive their frequency from the main oscillator but divide down - so you can not detune them, but only set them to half or a quarter (or an eight, though that's probably not of much use) times the frequency of the master oscillator.

A simplified (and probably incorrect) explanation: imagine a sawtooth wave that starts at zero and goes up. Once the voltage hits a certain value, the flip-flop "flips" and sends out a low voltage. The sawtooth drops again to zero and starts to rise again. When that certain value is hit again, the flip-flop flips again, and sends out a high voltage. It does either a logical true or false - which can be compared to a square wave. Since it only reacts to the "peak" of the saw and it takes 2 of those "peaks" to make it go up and down (an entire cycle) its frequency is half that of the master oscillator, or in other words, an octave below.

It doesn't matter if it's a DCO or a VCO doing the work though - both output a voltage that can be used for tasks like this. One thing I found with my Juno-60 is something interesting (and something I wish that was available in DCAM's Strobe) - the sub-oscillator is phase-shifted. With Strobe, it's not, which means that adding a square sub-oscillator pretty much only amplifies the sound.

I've no idea how other (analog) divide-down circuits (as found in string synths) do this, though.
Old 26th December 2010
  #7
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Quote:
Originally Posted by jupiter8 View Post
...
That's only a definition, it has no meaning in this case.

Yes and it is the wrong question and is utterly unimportant.
Listen, I think you're confusing the good old VCO/DCO question with my question on the suboscillators.

You're sidestepping my question with regards to the suboscillators. Let me ask this way instead:

1) Suboscillators are performed by the regular DCOs which are able to play two octaves at a time?

2) Suboscillators are DSP-generated lower-octave 'mirrors' of the oscillators?

Quote:
Originally Posted by jupiter8 View Post
..
QUOTE GeorgeHayduke: Did you actually read my post. UNQUOTE

Yes and it is the wrong question and is utterly unimportant.
My question wasn't pointed at you heh So this time you didn't read my post. No offense, just saying.. Please keep this thread to the point, this is not about DCO/VCO and it is not about whether it is a cool synth or not.
Old 26th December 2010
  #8
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Quote:
Originally Posted by Yoozer View Post
It's an interesting logical circuit that can do several things. Sub-oscillators derive their frequency from the main oscillator but divide down - so you can not detune them, but only set them to half or a quarter of the frequency of the master oscillator....
AHA, ok, flip-flop = divide down! Thanks for that. Like in old stringers and such. So, we are dealing with the regular DCOs which are able to play two octaves at a time, basically.
Old 26th December 2010
  #9
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Quote:
Originally Posted by GeorgeHayduke View Post
AHA! Thanks for that. Divide-down, I get that one! Like in old stringers and such. So, we are dealing with the regular DCOs which are able to play two octaves at a time.
Note that he said logical circuit which implies it is digital.

Take a transistor for example,is it analog or digital ? Well you can build amplifiers with them so they must be analog,right ? On the other hand you can build logical gates with them and if you have enough of them you can build a CPU so it must be digital.

A comparator can be seen as an analog circuit but also as a 1 bit AD converter with variable gain.

A digital circuit is made up of analog components but only deals with two states on or off hence they are also analog (IE a subset of analog.)

It just makes no sense to see a sub oscillator as either analog or digital. It is both. It is a circuit that changes state on a trigger and if you connect it to a square wave you get a square wave with half the frequency out of it.
Old 26th December 2010
  #10
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Ok, thanks, I'll try to get a better understanding of this.

But just to be sure: if something has an on/off switch that doesn't make it digital in my mind. Just like bucket brigade delays are not digital in my mind even if they are on/off, 1/0 or whatever you wanna call it.
Old 26th December 2010
  #11
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Yoozer's Avatar
Quote:
Originally Posted by jupiter8 View Post
Note that he said logical circuit which implies it is digital.
Correct. However, most of what we call "digital" for synths involves a D/A. If the flip-flop is used just like that and no D/A is involved, I can understand the confusion.

The opposite of "analog" is not "digital" in this case - it's "discrete". A signal with clearly defined steps and no values in between (or they count as "undefined") vs. a continuous signal.

A bucket brigade is not digital in that sense; it temporarily stores a voltage (which can have any value, no steps - so it's analog). It's time-discrete; each bucket is a little slice of time. For longer delay times, you get more buckets, or you lower the sample rate/clock speed.
Old 26th December 2010
  #12
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Quote:
Originally Posted by Yoozer View Post
Correct. However, most of what we call "digital" for synths involves a D/A. If the flip-flop is used just like that and no D/A is involved, I can understand the confusion...
Old 26th December 2010
  #13
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the flipflop is used as a frequency divider, it is used analog.
Old 26th December 2010
  #14
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Quote:
Originally Posted by jupiter8 View Post
Note that he said logical circuit which implies it is digital.

Take a transistor for example,is it analog or digital ? Well you can build amplifiers with them so they must be analog,right ? On the other hand you can build logical gates with them and if you have enough of them you can build a CPU so it must be digital.
Analog/digital is related not to actual signal (all signals are always analog), but to how we interpret it. With analog signal, we use the measurement of signal itself to represent something (e.g. if signal graph looks like sawtooth, then it represents sawtooth waveform), while with digital signals the meaningful data is somehow indirectly encoded into them (for example, amplitude drop from 1V to 0V might mean value "0" and rise from 0V to 1V might mean value "1", etc), and then we focus on those encoded values instead of the actual shape of signal.

Quote:
Originally Posted by jupiter8 View Post
It just makes no sense to see a sub oscillator as either analog or digital.
In case of Mopho, sub-osc's output is interpreted as an actual signal value that's added to osc mix, so it doesn't make sense at all to call it digital (there are no digital values decoded from it!), but it can be safely called analog.
Old 26th December 2010
  #15
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Quote:
Originally Posted by Megakazbek View Post
Analog/digital is related not to actual signal (all signals are always analog), but to how we interpret it. With analog signal, we use the measurement of signal itself to represent something (e.g. if signal graph looks like sawtooth, then it represents sawtooth waveform), while with digital signals the meaningful data is somehow indirectly encoded into them (for example, amplitude drop from 1V to 0V might mean value "0" and rise from 0V to 1V might mean value "1", etc), and then we focus on those encoded values instead of the actual shape of signal.
+1
Exactly, can we sticky this post, to avoid further confusion?

An analogue signal having only 2 states does NOT make it digital.
DCOs are not digital, suboscillators are not digital, squarewaves are not digital.
Logic circuits can be used in analogue circuits, eg. diode 'OR' give you the max of a number of voltages, diode 'AND' will give you the minimum of a number of voltages.

Digital means encoding an instantaneous signal value as a number, any changes to that are performed mathematically, and the whole lot goes via a D/A at the end.
Old 26th December 2010
  #16
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Quote:
Originally Posted by GeorgeHayduke View Post

That is an oxymoron.

How on earth is that oxymoron? It's audio path IS analogue. It runs DCOs, which have no affect on it's audio path. OSCs->Mixer->VCF->VCA. This is an all analogue audio path. DCOs are CONTROLLED by a digital means, which, again, have nothing to do with it's audio path. Same goes with the Junos. Don't confuse control signals with audio.
Old 26th December 2010
  #17
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Quote:
Originally Posted by Megakazbek View Post
Analog/digital is related not to actual signal (all signals are always analog), but to how we interpret it. With analog signal, we use the measurement of signal itself to represent something (e.g. if signal graph looks like sawtooth, then it represents sawtooth waveform), while with digital signals the meaningful data is somehow indirectly encoded into them (for example, amplitude drop from 1V to 0V might mean value "0" and rise from 0V to 1V might mean value "1", etc), and then we focus on those encoded values instead of the actual shape of signal.


In case of Mopho, sub-osc's output is interpreted as an actual signal value that's added to osc mix, so it doesn't make sense at all to call it digital (there are no digital values decoded from it!), but it can be safely called analog.
This is right, IMO. I had a similar discussion once at KVR with some guy who just didn't get the difference and insisted the Prophet 08 oscillators were digital. I eventually gave up. Some people just don't realize they don't own the absolute truth.

Read here if you're inclined to.
Old 26th December 2010
  #18
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Mopho

Quote:
Originally Posted by Acid Hazard View Post
The Mopho does have an all analogue audio path. It does run DCOs and the subs are probably digital. The Mopho is one of the best modern synths around and well worth the money!
+1
Old 26th December 2010
  #19
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Quote:
Originally Posted by shadowfac View Post
This is right, IMO. I had a similar discussion once at KVR with some guy who just didn't get the difference and insisted the Prophet 08 oscillators were digital. I eventually gave up. Some people just don't realize they don't own the absolute truth.

Read here if you're inclined to.
What is it with KVR? Every time i read that forum it's a bunch of nonsense cloaked as "fact".
Old 27th December 2010
  #20
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i really like my mopho too! i do wish i could afford something with higher end, modern, oscillators, ideally vco's, as most of the samples i've heard from them sound a lil different and more interesting to me. probably my favorite thing about the mopho is the filter actually, i like its character, has a kinda edge to it and the resonance sounds cool. the biggest gripe i have with it is the high speed CV modulation stuff often doesn't sound so good.. which they are upfront about in the manual (esp LFO->filter or PW). but whatever there is lots of stuff it does really well with a rich texture and filter warmth i just can't seem to tease out of my VA stuff. but now i have teh lust and want.. MODULAR.. but really even a small one is completely unaffordable (or just worthless) for me.

oh also does anyone else get some weird clicking artifact with the filter envelopes sometime? can't tell if this is a glitch or me being ignorant about using env modulation..

[EDIT:] most of these conversations that aren't DCO vs VCO are really just people trying to figure out if the initial ramp comes out of a DA converter or comes from a capacitor discharging i think.. wish they could just get phrased as such..
Old 27th December 2010
  #21
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Was anyone else severely disappointed with how the Mopho lacks MIDI control for most parameters, opting to use NRPN instead?
Old 27th December 2010
  #22
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Quote:
Originally Posted by Acid Hazard View Post
How on earth is that oxymoron? It's audio path IS analogue. It runs DCOs, which have no affect on it's audio path. OSCs->Mixer->VCF->VCA. This is an all analogue audio path. DCOs are CONTROLLED by a digital means, which, again, have nothing to do with it's audio path. Same goes with the Junos. Don't confuse control signals with audio.
Dude, you STILL haven't read what I posted, and you probably didn't read the rest of the thread.

Quote:
Originally Posted by GeorgeHayduke View Post
..
PPS: No 'DCO = digital'-comments please, this is not about DCOs/VCOs...
For the record, my opinion on the DCO debate, dated november 19:
Quote:
Originally Posted by GeorgeHayduke View Post
A hybrid is digital oscillators with analog components in the audio path. A DCO is not a digital oscillator, it is analog with digital control...
No big deal, but honestly, I specifically asked to keep DCOs off the menu in this thread because it is clearly digitally controlled ANALOG sound... THIS, however, is both not correct (read thread) AND it is an oxymoron:
Quote:
Originally Posted by Acid Hazard View Post
The Mopho does have an all analogue audio path. ...the subs are probably digital...
Old 27th December 2010
  #23
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You stated my comment about it having an all analogue audio path was an oxymoron, which it isn't. It's fact. And yes, i did read the thread. You're the only one harping on about not wanting to talk about DCOs. I'm talking about the AUDIO path.
Old 27th December 2010
  #24
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Quote:
Originally Posted by innervoice View Post
Was anyone else severely disappointed with how the Mopho lacks MIDI control for most parameters, opting to use NRPN instead?
I used a Behringer BCR2000 to control my Mopho when i had it. I used all CCs, no NRPNs. So no, i had no issues.
Old 27th December 2010
  #25
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Quote:
Originally Posted by innervoice View Post
Was anyone else severely disappointed with how the Mopho lacks MIDI control for most parameters, opting to use NRPN instead?
you can't set up cc control in the mod matrix?
Old 27th December 2010
  #26
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Quote:
Originally Posted by Acid Hazard View Post
You stated my comment about it having an all analogue audio path was an oxymoron, which it isn't. It's fact. And yes, i did read the thread. You're the only one harping on about not wanting to talk about DCOs. I'm talking about the AUDIO path.
For the last time:

Quote:
Originally Posted by Acid Hazard View Post
The Mopho does have an all analogue audio path. ...the subs are probably digital...
That is an oxymoron. Audio path analog with digital oscillators?

Anyways, the subs are NOT digital as there is no D/A involved. That said, I'm so done discussing this now, the thread was specifically not about DCOs.
Old 27th December 2010
  #27
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I said PROBABLY. As i didn't know for sure. As since you say they're not. Then i'm right

Anyway, doesn't matter. The Mopho sounds awesome, that's what matters!
Old 27th December 2010
  #28
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Quote:
Originally Posted by pinkerton View Post
you can't set up cc control in the mod matrix?
Isn't the mod matrix limited to 4 assignable controls? That didn't seem like enough when using the desktop module with an external controller.

Quote:
Originally Posted by Acid Hazard
I used a Behringer BCR2000 to control my Mopho when i had it. I used all CCs, no NRPNs. So no, i had no issues
Interesting. You had access to all parameters via MIDI, not just the 40 or so that come pre-mapped? Out of curiosity, why didn't you use NRPN, given the BCR has native support?
(I appreciate the info btw)
Old 27th December 2010
  #29
obs
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Quote:
Originally Posted by innervoice View Post
Was anyone else severely disappointed with how the Mopho lacks MIDI control for most parameters, opting to use NRPN instead?
It's not possible for something to use NRPN and yet lack MIDI control. Did you mean lacking MIDI CC control?
Old 27th December 2010
  #30
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Yea, it lacks CCs for some parameters.
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